A pretty common question is why the colours of uploaded PDF documents are different. 99% of the time the reason for this is because the PDF is saved in CMYK colourspace (optimized colours for printing) instead of RGB (optimized colours for web).
The CMYK colourspace is a more limited colourspace which basically makes the colours duller.
In order to fix this "error", you need to save the pdf in the right colour space (RGB) and then re-upload the pdf to GetAccept.